This is a study of the structure of bone mineral on the molecular level with emphasis on the elucidation of the processes involved in bone mineralization. The term structure as used here includes the identification of the chemical phases present in bone and the molecular arrangement of these chemical constituents. Such techniques as x-ray diffraction, infrared spectroscopy, electron microscopy and electron diffraction will be employed. Studies will be made on normal and pathological bone as well as on analogous synthetic calcium phosphates. In addition, the nature of the mineral in pathological calcification will be investigated.